Authentic Tiffany & Co. Beaded Open Heart Key Pendant, In Sterling Silver With Blue Enamel Finish. 18" Chain Is Sterling Silver And Marked Tiffany & Co. & Ag 925. Comes with pouch and box. Tiffany & Co. Hallmark: Tiffany & Co. Ag925. Measurement: 2.35" long w/bail x 0.75" wide x 0.15" high Weight: 6.6 grams From the Heart Key Collection by Tiffany & Co. This lovely open heart key pendant is crafted from sterling silver featuring an open heart with Tiffany's blue- green enamel around the edge of the heart bordered with polished silver beads on both sides. It is signed by the designer with the silver content.